Method of smelting pyritic ores.



J. P. CHANNING & P. J. FALDING.

METHOD 0F SMELTING PYRITIG DRES.

APPLIUATION FILED MAY4, 1909.

963-9020.. l k Patented Jun28,1910.

@narran 4e'iaians ramena ortica,

JOHN PARKE CHANNING AND FREDERIC JOI-IN FALDING, OF NEW YORKJ N. Y.

METHOD OF SIVIELTING PYRITIC DRES.

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To all whom it may concern:

Be it known that we, JOHN PARKE CHAN- NING and FREDERIC JOHN FALDING, both citizens of the United States, residing at New York city, county of New York, and State of New York, have invented certain new and useful Improvements in Methods of Smelting Pyritic Ores, fully described and represented in the following specification and the accompanying drawing, forming a part of the same.

This invention relates to an improved method of smelting pyritic ores and utilizing the gases therefrom, it being the object of the invention to produce a higher grade matte, or an iron slag available for the production of pig iron, and gases having such composition that they may be utilized, as for making sulfuric acid.

Some pyritic ores contain, in commercial quantities, copper or nickel or the precious metals, or several of these metals, while in other such ores they do not so exist.

In smelting suld copper ores pyritically, as carried out previous to our invention, the ore, not previously roasted, is treated in a blast furnace with a certain amount of carbonaceous material, the oxidation of the charge being accomplished by blowing certain quantities of air therethrough. This action results in an oxidation of a portion of the iron and sulfur content in the ore, which provides nearly all of the heat necessary for the process. The portion of the iron and sulfur which is not oxidized, theoretically combines with the copper and forms a substance known as matte, which is drawn off from the furnace and further treated to obtain the copper. The oxidized sulfur (SO2) passes from the furnace in the form of a gas, together with other gaseous substances. l/Vhile this oxidation of the iron and sulfur in the charge, when they exist in suflicient quantities, theoretically should furnish heat enough to smelt the charge, in practice certain carbonaceous material has been added in the form of coke to furnish heat enough to smelt the charge, and this coke, during the smelting operation, is oxidized into carbon dioxid (CO2). This mode of smelting is known in the art as pyritic smelting. In this method of smelting, as practiced before our invention, considerable quantities of sulfur would leave the furnace with the gases unoxidiz'ed or sublimed, heat thus being lost, and, in addition, it frequently happened Speceation of Letters latent.

Application led May 4, 1909.

Patented J une 28, i910.l Serial No. 493,801.

that the iron was not suiiiciently oxidized, thus producing an inferior grade matte. In addition, so much of the oxygen in the air blown into the furnace was taken up in oxidizing the excess of coke into carbon dioxid that there was not enough oxygen left in the gases to convert the sulfur dioxid into sulfur trioxid to obtain sulfuric acid therefrom, if it were desired to use the gases for this purpose. Such oxygen could not, under such conditions of excess of coke, be re` placed by supplying more air to the gases, for the reason that in the air supplied so much nitrogen was present that the resulting gases were diluted to such an extent as to be unt for such use, being too weak in sulfur dioxid.

If pyritic ores containing, in commercial quantities, nickel or the precious metals, or several of these metals, or pyritic ores in which neither they nor copper so exist, were smelted pyritically in the manner above described, there would be a similar loss of heat due to the escape of sulfur from the furnace, and an inferior grade matte would be produced with ores containing nickel or the precious metals; or, in the case of such ores in which copper or the other metals referred to do not exist in commercial quantities, the iron slag would be liable to contain sulfur in detrimental quantities. The resulting gases would also be diluted to such an extent as to render them unfit for use in obtaining sulfuric acid therefrom, if it were desired to use the gases for this purpose, for the reasons heretofore given.

Our invention consists in supplying air in sufficient quantity so that the sulfur and iron in ore containing copper or nickel or the precious metals is practically completely oxidized, except the sulfur and iron intended to combine with such metals in forming the final matte, and so that the sulfur and iron in ore in which copper, nickel or the precious metals do not exist in commercial quantities is practically completely oxidized, and so that the sulfur dioxid in the resulting gases may subsequently be converted from sulfur dioxid into sulfur trioxid, without diluting the gases so as to unfit them for making sulfuric acid. The sulfur and iron thus practically completely oxidized, we shall hereafter refer to as the available sulfur and iron.

In carrying out our invention, we employ a blast smelting furnace, the twyers of which are sufiiciently large to enable the proper amount of air to be forced therein, which amount is controlled by valves in the pipes leading to the tWyers. Such furnace is constructed so as to prevent, as far as practicable, any air entering therein except throughV the twyers. 1f air leaks into the furnace at the top and around the charging. doors in any considerable quantity, there is danger that thel gases will be` made so weak or d1- luted as to be unsuitable for conversion into sulfuric acid, and such u false air' should bey excluded. Ifrthe ore does not contain enough available sulfur and iron to produce,by oxidation, the heat necessary for the sinelting operation, `or if' the' ore does contain enoughavailable sulfur and' iron for this purpose, carbonaceous materiahpsuch as coke, may be added. In' either case, this should be in aA certain proportion to the sulfur content in the charge to be smelted,` the proportion of such carboi'iaceous'y material to be maintained as low as possible, and yet notinterfere with the smelting operation, in order to obtainA gases containing sufficient oxygen lrelatively yto the sulfur dioxid-` In practice we have found that as low as about -1-% of carbon ,tor about t% of available sulfur in the charge is a proportion which produces gases' having sufiicient oxygen therein to convert `or o xidize thesulfur di'- oxid into sulfur trioxid.` To give a concrete example, in a sulfid copper ore containing 25% of sulfur, about 20% of which will' be oxidized or available, the balance of which will combine with thei'ron and vcopper to form the matte, we find that as lo'w as 2,900 of coke is suflicient to allow for the proper operation of a smelting furnace, and at the same time to obtain` gases sufliciently rich in oxygen. `It is found in practice, furthermore, that the amount of free oxygen should, to obtain the best results, be considerably more than the amount theoretically required to convert the sulfur, dioxid` into' sulfur trioxid. v For example, assuming that the gases contain 6% of sulfur dioxid, such gases would, theoretically, require 3% of free oxygen to convert them into sulfur trioxid. Gases containing such percent-ages of sulfur dioxid should, however, to obtain the best results, carry from 7 to 8% of free oxy gen, or an excess of 4% to 5% of free oxygen over that theoreticallyI required, In addition to having sufficient oxygen i'n the gases to convert thesulfur dioxid into sulfur trioxid, the vgases should preferably be as rich as approximately 5% in sulfur dioxid, but not richer than approximately u as a much higher percentage of sulfur dioxid would preclude the possibility of there being sufficient free oxygen vto oxidizey the sulfur dioxid `into sulfur trioxid. lf the resulting gases, whether carbonaceous material is used or not, are too rich in sulfur dioxid, they can be diluted by admitting more air through the tvvyers referred to than is necessary to practically completely oxidize the available sulfur and iron in the ore, or such additional air can be admitted through extra twyers, with which the furnace can be provided, located above those before'referred to, and below the top of the charge, the amount of air so admitted being controlled by valves in the pipes leadingto the twyers,or such air can be introduced into thetop of the furnace, or at any point after the gasesv leav'e'the furnace, between'the furnace and the Glover towers (not illustrated), if the chamber process of makingsulfuric acid is employed; or, if thegaf'ses' are cooled too much for the concentrating function of the Glover tow'- ers (if suoli air were admittedl before the gases lenter the` same) then such air may be admitted after such gases pass such Glover towers;l or, if the contact process is employed', then such air ymay be admitted' lto suchA gases between the furnacel and the apparatus of such contact process, the' amount of air so admitted being controlled by suitable devices, as valves. the ore is delicieiit in silica, an ordinary quartz` flux is added' ,for the smelting operation;

If a plurality of furnaces is employed, and the gases therefrom have varying contents of sulfur dioxid and oxygen, the content' of each furna'cepbteing different? from that of the others, they can be treated as set forth in a' co-pen'd'ing application filed by us May 14, 1908,v serially numbered 432,781.

In` the drawings we haveV illustrated a blast smelting furnace, in which- Figure l shows such furnace partly in vertical s'ection, the apparatus for introducing and' regiilatiiig the quantity of air forced into the furnace being shown inr elevation; and Fig'. 2 shows af planview ofthe top of thefurnace, the apparatus for introducing and controlling the quantity of air forced into `the furnace not being shown.`

`Referring to these drawings, the sides and end o'f the furnace are shown as made up of water ja'cleted sections l, with a suitable base, and near the latter its an opening 2, through `which the slag or the matte and slag pass intoa spout 3 from which' it is delivered into the proper receptacle. Above these water jacketed sections is a furnace top 4l, also made in sections, having openings 5 through' which the charge to be smelted is dumped, said openings beingl closed by hinged charging doors 6, which should be approxiniately air tight. A bustle pipe 7 4is connected by pipes S, having aircontrolling valvesS", leadingto the twyers, near the bottom of the furnace, there being preferably Atwo of these pipes 8 and air controlling valves S and twyers, for each ofthe lower water acketed sections of the furnace, the

valves 8 enabling the regulating of the quantity of air forced into the furnace burden through the twyers for the smelting operation. We have indicated in dotted lines another similar set of pipes connected with the bustle pipe 7, such pipes leading to twyers located above those first referred to, and below the top of the charge, for introducing air for diluting the resulting gases if they are too rich in sulfur dioxid, said pipes having valves for regulating the quantity of air introduced through such tvvyers.

Leading from the furnace top Ll is a flue 10 for conveying the gases from the furnace. This flue 10 is connected with a chamber 13 from which the gases, entering therein from such flue, are, if it is desired to use them lfor making sulfuric acid, conducted to an apparatus for making such acid. rIhe flue 10 has a pipe 9 connecting with a flue or bypass 11. The pipe 9 is provided with a damper 15, and the flue 10 is also provided with a damper 16 beyond the pipe 9, so that such flue may be connected With the chamber 13 and disconnected from the by-pass 11, or disconnected from the chamber 13 and connected to the by-pass 11, as and when desired.

If a plurality of furnaces is employed, as before referred to, each of these furnaces will be provided with a flue 1() connected with the chamber 13 and having a damper 16, and with a pipe 9 provided with a damper 15 connecting with the by-pass 11, so that the gases from the different furnaces can be controlled and commingled, and treated in apparatus as set forth in said copending application.

In treating ores according to our invention containing' copper or nickel or the precious metals in commercial quantities, it may sometimes be preferable at first to leave more sulfur and iron in the matte than is desirable to combine with such metals in forming the final matte, when there is a likelihood of such metals being oxidized and being lost in the slag. In such case, after such lower grade matte is produced, it is again treated in the same furnace or in another furnace and air supplied thereto in sufhcient quantity so that the sulfur and iron remaining therein are practically completely oxidized, except the sulfur and iron intended to combine with the copper and nickel or the precious metals in forming the final, higher grade matte. In such second treatment, the proportion of the carbonaceous material, (if employed), to the sulfur is maintained as low as possible and the air may be supplied as heretofore described, so that the sulfur dioxid in the resulting gases may be converted from sulfur dioxid into sulfur trioxid without diluting the gases so as to unt them for making sulfuric acid, or the proportion of such carbonaceous material to the sulfur and the resulting gases may be ignored for the purpose of making sulfuric acid. This treatment in several steps is to be regarded as the equivalent of the treatment in one step for the purposes as stated.

The result produced by our invention is that a higher grade matte in case copper or nickel or any of the precious metals exist in commercial quantities in the ore treated may be produced, or in case they do not so exist in the ore treated, then the resultant iron slag will be available for the production of pig iron in an ordinary blast furnace; a saving in carbonaceous fuel, such as coke, if it be used; sublimed sulfur will either not substantially pass off With the gases, or a less amount will pass off than prior to curinvention, and the gases may be profitably used in the production of sulfuric acid Whether ores so low in sulfur, that treated by the ordinary methods, such ores will not produce such gases profitably are treated, or whether ores rich in sulfur are treated.

What we claim is In the art of smelting pyritic ores pyriticably, and utilizing the gases therefrom, the improvement which consists in supplying air in sufficient quantity so as to practically completely oxidize the available sulfur and iron in the ore, and produce a matte, and also produce a gas of such composition as will enable the sulfur dioxid contained therein to be oxidized into sulfur trioxid, in a condition to be used for making sulfuric acid, substantially as described.

In testimony whereof, we have hereunto set our hands in the presence of two subscribing witnesses.

JOHN PARKE GHANNING. FREDERIC JOHN FALDING. Vitnesses P. B. PHILIPP, J. A. GRAVES.

Correction in Letters Patent No. 963,020.

It is hereby certified that L etters Patent No. 963,020, granted June 28, 1910,

upon the application of John Parke Channing and Frederic John Folding, of New York, N. Y., for an improvement in Methods of Smelting'Pyritio Gres, were erroneously issued to said inventors; Whereas they should have been issued to said Jo/m Pwr/ee O/cmm'ng as solo owner' of sued o'rwe'lztz'on, as shown by the record 0f assignments in this oliee; and that the said Letters Patent should be rend With this lcorrection therein that the sume may conform to the record ot' the @use in the Patent Office.

Signed and sealed this 19th day of July, A. D., 1910.

[SEAL] F. A. TENNANT,

Acting Commissioner of Patents. 

